Poly (phosphine oxide) flame-retardants

ABSTRACT

Compounds having the formula   WHEREIN R and R1 are, individually, methyl, ethyl or methoxy radicals; AR is benzene, naphthalene or anthracene and when AR is benzene, n and m are, individually whole integers of 0-2, inclusive, x is a whole integer of 2-6, inclusive and R and R1 can combine to form a saturated, six-membered, hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring; when AR is naphthalene, n and m are, individually, whole integers of 0-3, inclusive, and x is a whole integer of 2-4, inclusive; and when AR is anthracene, n and m are, individually, whole integers of 0-4, inclusive, and x is a whole integer of 26, inclusive, and flame-retarded polymers containing the same, are disclosed.

United States Patent [1 1 Hoffman POLY (PHOSPHINE OXIDE) FLAME-RETARDANTS [75] Inventor: Joseph Adrian Hoffman, Somerville,

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: June 28,1973

21 Appl.No.:374,709

[52] US. Cl 260/465 H; 260/45.7 P; 260/465 F;

260/887; 260/893 [51] Int. Cl. C07C 121/66 [58] Field of Search 260/465 H, 465 F, 45.7 P

[56] References Cited UNITED STATES PATENTS 3,284,543 11/1966 Gillham et a1. 260/45.7 X 3,322,861 5/1967 Gillham et a]. 260/45.7 X

Primary Examiner-Elbert L. Roberts Assistant ExaminerDolph H. Torrence Attorney, Agent, or FirmFrank M. Van Riet July 15, 1975 [57] ABSTRACT Compounds having the formula wherein R and R are, individually, methyl, ethyl or methoxy radicals; AR is benzene, naphthalene or anthracene and when AR is benzene, n and m are, individually whole integers of 0-2, inclusive, x is a whole integer of 2-6, inclusive and R and R can combine to form a saturated, six-membered, hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring; when AR is naphthalene, n and m are, individually, whole integers of 0-3, inclusive, and x is a whole integer of 2-4, inclusive; and when AR is anthracene, n and m are, individually, whole integers of 0-4, inclusive, and x is a whole integer of 2-6, inclusive, and flame-retarded polymers containing the same, are disclosed.

7 Claims, No Drawings POLY (PI-IOSPI-IINE OXIDE) FLAME-RETARDANTS CROSS-REFERENCE TO RELATED APPLICATION This application is related to my application Serial No. 374,728 filed of even date herewith, now US. Pat. No. 3,835,l19 and entitled poly(phosphine oxide)- ammonium polyphosphate flame-retardants.

BACKGROUND OF THE INVENTION The use of alkylenebisphosphine oxides to flameproof thermoplastic polymers is known, see US. Pat. No. 3,284,543. These compounds, although effective flame-retardants for thermoplastics, are effective only at high concentrations of about 20-25% in most polymers. Moreover, these prior art compounds have been f (III) CHZP+CHZCHZCN)2 found to be relatively incompatible with many polymers such as, for example, polypropylene. As a result, they are extremely difficult to incorporate into such polymers by conventional extrusion and injection molding techniques since they tend to exude from the polymer. Consequently, uniform dispersions of the alkylenebisphosphine oxides are difficult to obtain. A third, sometimes more detrimental, disadvantage of these known flame-retardants is that they are relatively water-soluble and in certain applications of the flameproofed polymers, such as in components of clothes washers and dishwashers, they tend to be extracted from the polymer. As a result, the polymer becomes more readily flammable and ultimately fails to pass the Underwriters Laboratory test of acceptable flameretardance.

SUMMARY I have now discovered that these and other less objectionable deficiencies of the alkylenebisphosphine oxides can be overcome, and excellent flame-retardant properties can be achieved, by incorporating into thermoplastic polymers a compound conforming to the formula set forth hereinabove. These novel compounds impart flame-retardancy to thermoplastic polymers at relatively low concentrations, are easily incorporated into the polymer substrate and do not leach out of the polymer when it is used in conjunction with water after having been formed into a particular article of manufacture.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS The compounds found to be effective in flameproofing thermoplastic polymers according to the present invention conform to at least one of the following formulae wherein R R, R, R R and R" are, individually, methyl, ethyl or methoxy radicals, and R and R can combine to form a saturated, six-membered, hydrocarbon ring in conjunction with two adjacent carbon atoms of the benzene ring; a and b are, individually, whole integers of 0-2, inclusive; 0 and d are, individually, whole integers of 0-3, inclusive; e and f are, individually, whole integers of 04,inclusive; w is a whole integer of 26, inclusive; y is a whole integer of 2-4, inclusive; and z is a whole integer of 2-6, inclusive.

Among the preferred compounds are those represented by Formula I, including 5,8-bis[bis( 2- cyanoethyl )phosphonylmethyleneltetralin; l ,4- bis[bis(2-cyanoethyl)phosphonylmethylene1-2 ,3 ,5 ,6- tetramethyl benzene; 1 ,2,4,5-tetrakis bis( 2- cyanoethyl)phosphonylmethylene]benzene; 2,4,6- tris[bis( 2-cyanoethyl)phosphonylmethylene]mesitylene; l ,4-phenylenebis[bis(2-cyanoethyl)phosphonylmethylene]; 2,4-bis[ bis( 2-cyanoethyl )phosphonylmethylene]-l,3,5-trimethyl benzene and the like.

Compounds falling within the scope of Formulae II and 111 include l,5-bis[bis(2-cyanoethyl)phosphonylmethylene] naphthalene; 9, lO-bis[bis(2-cyanoethyl)- phosphonylmethylene] anthracene; 2,6-bis[bis(2- cyanoethyl)phosphonylmethylene] naphthalene; 2,3,6- tris[bis(2-cyanoethyl)phosphonylmethylene] naphthalene; 2,3,6-tris[bis(2-cyanoethyl)phosphonylmethylene] anthracene; 2,6,9,l-tetra[bis(2-cyanoethyl)- phosphonylmethylene] anthracene; l,6-bis[bis(2- cyanoethyl )phosphonylmethylene ]-2-methoxy naphthalene; 2,3-bis[bis(2- cyanoethyl)phosphonylmethylene]-6,7- diethylanthracene and the like.

The compounds of the instant invention are readily prepared by reacting bis(2-cyanoethyl)phosphine oxide with the appropriately substituted halomethyl aromatic compound, in accordance with the general reaction.

base (NCCH CH PH O 11 AR- CH2P(CH2CH2CN)2 X wherein X is a halogen and x, m, n, R, R and AR are as set forth above.

The intermediate halomethylated aromatic compounds may conveniently be prepared by reacting the corresponding benzene, naphthalene or anthracene with formaldehyde and a hydrogen halide e.g. hydrogen chloride; hydrogen bromide etc., according to known procedures such as those disclosed in US. Pat. Nos. 2,945,894; 2,951,100; 2,973,391; and 3,069,480. Alternatively, chlorination of the alkyl group or groups of the appropriate methyl benzene, methyl naphthalene or methyl anthracene in the presence of suitable catalysts, see US. Pat. No. 2,926,202, or with chlorine absorbed on zeolite and under reactive conditions, see U.S. Pat. No. 2,956,084, may be effected.

The novel compounds of the instant invention are prepared according to the above general reaction in an organic solvent which is inert to the reaction and the components thereof. Methanol has been found to be a convenient solvent, however, other alcohols may also be used. The reaction is best conducted in the presence of a proton acceptor such as a strong base e.g. potassium or sodium hydroxide, in amounts equivalent to the amount of hydrogen halide evolved.

The reaction is conducted at a temperature ranging from abuot C. to about 60C. under atmospheric pressure. Subatmospheric or superatmospheric pressure can be used, if desired. N0 catalysts are necessary.

The compounds represented by Formula A, above, may be incorporated into the thermoplastic polymers to which they are to impart flame-retardance in amounts ranging from about 10 percent to about 15 percent, by weight, based on the weight of the polymer.

The poly (phosphine oxides) may be incorporated into the polymers by any known method. For example, the oxide may be combined with the polymer by milling the two on a two-roll mill, mixing in a Banbury mixer, extrusion, injection molding and the like. The oxide may also be incorporated into the polymer by adding it to the polymerization media during the polymer manufacture, provided the ingredients, catalysts etc. therein are inert thereto.

The thermoplastic polymers into which the novel poly (phosphine oxides) may be incorporated to produce the novel compositions of the instant invention are generally those produced from at least one ethylenically unsaturated monomer, wherein the monomer, or monomers, are polymerized, by any known method, via the ethylenic unsaturation therein. Preferred examples of polymers conforming to this definition include thepolyolefins i.e. those polymers produced from ethylene, propylene etc. including copolymers thereof with suchmonomers as vinyl acetate etc. and homopolymers thereof i.e. polyethylene; polypropylene etc.; I may also use such polymers as the linear aromatic polyesters such as polyethylene terephthalate; polybutylene terephthalate; p0ly( 1 ,4-cyclohexanedimethylene terephthalate etc.; the polyalkylene oxides such as polyethylene oxide; nylon; butadiene polymers such as the so-called impact polymers i.e. acrylonitrilebutadiene-styrene polymers; acrylonitrile-styrenemethyl methacrylate grafted polybutadiene etc. Further examples of applicable polymers which may be flame-proofed using my novel compounds are set forth in US. Pat. No. 3,284,543, referred to above, and hereby incorporated herein by reference.

It is within the scope of the present invention to incorporate such ingredients as plasticizers, dyes, pigments, fillers, stabilizers, antioxidants, antistatic agents etc. into my novel compositions without detracting from the advantageous properties exhibited thereby.

The following examples are set forth for purposes of illustration only and are not to be construed as limitations on the present invention except as set forth in the appended claims. All parts and percentages are by weight except where specified otherwise.

ILLUSTRATIVE METHOD PREPARATION OF p-DIBROMOMETHYL DURENE CH3 CH3 Br CH2 CH2 Br CH CH3 A solution of 1760 ml. of concentrated sulfuric acid in 1740 ml. of glacial acetic acid is prepared. A slurry of 444 parts of durene, 580 parts of paraformaldehyde and 1900 parts of sodium bromide in 3720 ml. of glacial acetic acid is heated to C. and the sulfuric acid solution is added thereto over a period of 3 hours to give a thick, cream-colored slurry. The slurry is heated at C. for 1 hour, cooled to 5C. and filtered. The resultant filter cake is washed three times with 400 ml. of acetic acid, reslurried twice in 4000 ml. of water, reslurried again twice in 2500 ml. of 5 percent sodium bicarbonate solution and again twice in 5000 ml. of water. The recovered filter cake is then dried at 50C. 992 parts of the desired product, p-dibromomethyl durene, m.p. 214.5-215C., are recovered. The product is a white powder. The yield is 93 percent.

EXAMPLE 1 A slurry of 880 parts of bis(2-cyanoethyl)phosphine oxide and 819 parts of the p-dibromomethyl durene produced above in 13,000 ml. of methanol is prepared and stirred as 374 parts of potassium hydroxide in l800 ml. of methanol are added thereto at such a rate as to maintain the temperature below 40C. The slurry is heated to reflux and, after 30 minutes, cooled to 5C. and filtered. The resultant filter cake is reslurried three times in 1800 ml. of acetone, filtered, reslurried twice in liters of water, filtered and dried to yield 1130 parts of l ,4-bis[bis( 2- cyanoethyl)phosphonylmethylene]-2,3,5,6- tetramethyl benzene. The product is a white powder having a melting point of 299300C. The crude product is then recrystallized from boiling dimethylformamide to yield 1817 parts in two crops. Final melting point is 308-308.5C.

EXAMPLE 2 EXAMPLE 3 Again following the procedure of Example 1, bis(2-cyanoethyl)phosphine oxide and 2,4,6,- tribromomethyl benzene are reacted to produce 2,4,6- tris[bis(2-cyanoethyl)phosphonyl methylene1mesitylene having a melting point of 23724lC.

EXAMPLE 4 1,4-dibromomethyl benzene is reacted with bis(2-cyanoethyl)phosphine oxide according to the procedures set forth in Example 1 to yield 1,4-

phenylenebis[ bis( 2-cyanoethyl )phosphonylmethylene] having a melting point of 20l-203C.

EXAMPLE 5 Again using the technique of Example 1, 1,3-dimethyl-4,6-dibromomethyl benzene is reacted with bis(2- cyanoethyl) phosphine oxide to yield 4,6-bis[bis(2- cyanoethyl)phosphonylmethylene]-l,B-dimethyl benzene having a melting point of l153C.

EXAMPLE 6 The procedure of Example 5 is again followed except that the halobenzene intermediate is replaced by 1,4-

6 dimethyl-Z,S-dibromomethyl benzene. 2,5-Bis[bis(2- cyanoethyl)phosphonylmethylene]- l ,4-dimethyl benzene, having a melting point of 242245C., is recovered.

EXAMPLE 7 When the procedure of Example 5 is again followed except that the halobenzene intermediate thereof is replaced by 2,5-dibromomethyl-l,4-dimethoxybenzene, 2,5-bis[bis( 2-cyanoethyl)phosphonylmethylene]-l ,4- dimethoxybenzene, having a melting pointof 229-23lC., is recovered.

EXAMPLE 8 Again following the procedure of Example 1, 1,5- dibromomethyl naphthalene is reacted with bis(2- cyanoethyl) phosphine oxide utilizing a 50/50 mixture of methanol and dimethylsulfoxide as solvent. The resultant product, 1 ,5-bis[bis( 2- cyanoethyl )phosphonylmethylene naphthalene has a melting point of 226228C.

EXAMPLE 9 Following the procedure of Example 8, there is obtained 9 1 O-bis bis( Z-cyanoethyl phosphonylmethylene]anthracene from bis(2-cyanoethyl)phosphine oxide and 9,lO-dibromomethylanthracene. The product has a melting point of 320330C.

EXAMPLE 10 The procedure of Example 8 is again followed except that the halobenzene intermediate is replaced by 5,S-dibromomethyltetralin. 5,8-Bis[bis(2-cyanoethyl)- phosphonylmethylene] tetralin having a melting point of 228230C. is recovered.

EXAMPLE 1 1 Table I PRODUCT EX. BROMOMETHYL BENZENE l 2 Hexabromomethylbenzene l3 l,4-dibromomethyl-2,3 ,5 ,6-

tetraethoxybenzene l4 l,4-dibromomethyl-2,5-

diethylbenzene l5 l,2,4,5 ,G-pentabromomethyl benzene l6 2,5-dibromomethyll ,4-diethyl-3.o-dimcthoxybenzene l 7 2 ,3 ,5 -tribromomethyl naphthalene l 8 2,3 ,fi tribromornethyl anthracene 1) 2,6,9, 1 O-tetrabromomethyl anthracene 20 Z-methoxyl ,o-dibromo naphthalene Hexal bis( 2-cyanoethyl )phosphonylmethylene lbenzene l ,4-bis[ bis( 2-cyanoethyl )phosphonylmethylene]-2,3,5,6-tetrathoxybenzene l ,4-bis[ bis( 2-cyanoethyl)phosphonylmethylene]-2,5-diethylbenzene 1 ,2,4,5 ,6-penta[ bis( 2-cyanoethyl) phosphonylmethylene]benzene 2,5-bis[bis(2-cyanoethyl)phosphonylmethylene1-l ,4-diethyl-3 ,-dimethoxybenzene 2,3,S-tris[bis(2-cyanoethyl)phosphonylmethylenelnaphthalene 2,3,6-tris[bis(2-cyanoethyl)phosphonylmethylene ]anthracene 2,6,9. 1 0-tetra[bis( 2-cyanoethyl )phosphonylmethylenelanthracene l,6-bis[ bis( 2-cyanoethyl)phosphonylmethylene1-2-methoxy naphthalene EXAMPLE 21 To polypropylene containing 0.1% of pentaerythriyl tetrakis (3,5-di-t-butyl-4-hydroxyphenyl)propionate and 0.25 percent of distearylthiodipropionate is added 10 percent, by weight, based on the weight of the polymer, of the l,4-bis-[bis(2-cyanoethyl) phosphonylmethylene]-2,3,5,6-tetramethylbenzene of Example I by milling at 350F. on a standard plastic mill. The resultant composition is then compression molded into bars X inches X /2 inch) at 400420F. The bars are then tested according to ASTM D635-70 horizontal burning test modified using 3-4 test specimens. The flammability rating is self-extinguishing.

When a similar amount of the compound of Example 1 of US. Pat. No. 3,284,543 is incorporated into the same polymer in the same manner and molded and tested, as above, the flammability rating is free-burning.

EXAMPLES 2226 Various of the novel poly (phosphine oxides) of the instant invention are dry blended at by weight, based on the weight of the terephthalate, with polyethylene terephthalate and the dry blend is melted and stirred under nitrogen for 5-6 minutes at 3003l0C.

The resultant mixture is then cooled, ground to a powder and laminated onto a fiberglass sheet by compression molding at 600F. The recovered laminated sheets Table II Ex. Product of Example No. Oxygen-Index Value 22C Control-terephthalate l9.6

alone 23 1 24.1 24 2 24.1 25 3 23.3 26 4 23.9

Table III Oxygen Index Value Before After Ex. Flame-Retardant Added Extraction Extraction 27 ControlTerephthalate l9.6 19.6

Alone 28 That of Example 1 above 24.1 23.9 29 That of Example I of 24.1 21.2

EXAMPLES 30-41 When the products produced in Examples 5-7 and 12-20 were tested in polyethylene terephthalate according to the above Oxygen Index Test, results similar to those shown in Table II were achieved.

EXAMPLES 42-58 Table IV Ex. Arylenebisphosphene Oxide Polymer Test Results 42 That of Ex. 2 l5% Polyethylene passed 43 That of Ex. 3 l0% Polybutylene terephthalate do 44 That of Ex. 5 10% Polypropylene do 45 That of Ex. 6 l0% Poly(l,4-cyclohexanedimethylene) do terphthalate 46 That of Ex. 7 10% Same as Ex. 42 do 47 That of Ex, [2 l0% Polypropylene do 48 That of Ex. 13 l0% Polypropylene do 49 That of Ex. 14 15% Same as Ex. 42 do 50 That of Ex. 15 l0% Polyethylene do 5l That of Ex. 17 l0% Polypropylene do 52 That of Ex. 18 10% do do 53 That of Ex. 19 10% do do 54 That of Ex. 20 l0% do do 55 That of Ex. 8 10% do do 56 That of Ex. 9 10% do do 57 That of Ex. 10 12% do do 58 That of Ex, ll l5% do do are then cut into strips 2 X 6 inches X 0.030 inch and .tested according to the Oxygen Index method of ASTM D2863-70 modified to accept the above test specimens. In this test, the higher the oxygen index, the better the flame-retardance. The results are set forth in Table II, below. Additional sample strips are also subjected to hot water leaching according to Underwriters Laboratory Water Extraction Test, Subject 746, March 1, 1957, paragraph E6 and then burned. The water extraction test requires that the samples be immersed in water at 70C. for 7 days, the water being changed daily for the first five days. The samples are dried in a dessicator after the immersion tests and before they are subjected to the above ASTM Oxygen Index test. The results are set forth in Table III, below.

I claim: 1. A compound having the formula benzene ring, when AR is naphthalene, n and m are, in- 4. A compound according to claim 1 wherein AR is dividually, whole integers of O-3, inclusive, and x is a benzene, R and R are methyl, x is 3, n is 2 and m is 1. whole integer of 2-4, inclusive, and when AR is anthra- 5. A compound according to claim 1 wherein AR is cene, n and m are, individually, whole integers of 0-4, benzene, x is 2 and n and m are 0.

inclusive, and x is a whole integer of 2-6, inclusive. 5 6. A compound according to claim 1 wherein AR is 2. A compound according to claim 1 wherein AR is benzene, R is methyl, x is 2, n is 2 and m is 0.

benzene, R and R are methyl and x, n and m are 2. 7. A compound according to claim 1 wherein AR is 3. A compound according to claim 1 wherein AR is naphthalene, x is 2 and n and m are 0. benzene, x is 4 and n and m are 0. 

1. A COMPOUND HAVING THE FORMULA
 2. A compound according to claim 1 wherein AR is benzene, R and R1 are methyl and x, n and m are
 2. 3. A compound according to claim 1 wherein AR is benzene, x is 4 and n and m are
 0. 4. A compound according to claim 1 wherein AR is benzene, R and R1 are methyl, x is 3, n is 2 and m is
 1. 5. A compound according to claim 1 wherein AR is benzene, x is 2 and n and m are
 0. 6. A compound according to claim 1 wherein AR is benzene, R is methyl, x is 2, n is 2 and m is
 0. 7. A compound according to claim 1 wherein AR is naphthalene, x is 2 and n and m are O. 